LOS ANGELES — Forecasters warned Tuesday of a new round of Santa Ana winds they fear could fan further fires across Southern California, while authorities concluded that a destructive Malibu blaze started over the weekend at a popular hangout in a canyon above the city.

The remnants of the nearly 8-square-mile Malibu blaze was fully contained, as the National Weather Service issued "red flag" warnings for fire danger from 3 a.m. Wednesday until evening in parts of Los Angeles County. The warning was extended to the northwest in Ventura County because of predicted strong winds overnight and low humidity.

Fire weather watches were issued for much of the rest of the region to the east and southeast, including San Bernardino, Riverside, Orange and San Diego counties.

The dry winds could produce gusts as high as 50 mph in and below some canyons and passes, the Weather Service said. The winds were expected to die by midday Wednesday, but humidity levels could remain low into Thursday.

County Fire Inspector Sam Padilla said two teams of five engines and about 20 crew each were on standby in case the winds materialized.

Blaze likely began near caveIn the Malibu fire, investigators found "substantial evidence" and determined the weekend blaze began early Saturday at an area known locally as "the cave" in Corral Canyon, said Steve Whitmore, a spokesman for the Los Angeles County Sheriff's Department.

"Come forward," he said. "You can provide crucial information. You know it and we know it." Witnesses could remain anonymous, Whitmore said.

Whitmore said he could not discuss the evidence found at the site, in the rugged mountains that swoop down into Malibu and the Pacific Ocean.

The canyon abuts Malibu Creek State Park.

"We don't know if (the fire) was deliberate, accidental or stupid," said Roy Stearns, a California State Parks spokesman. "It's kind of hard to believe that someone who lives in that area wasn't aware of the danger of the winds and started a campfire. If it was started deliberately, we just want to catch them and put handcuffs on them."

Called a party spotThe area around the cave was sealed off Sunday, and sheriff's deputies, working with bloodhounds, patrolled the area close by.

"It's an incredible spot," said local resident Ricardo Means. "I've been up there and seen howling groups of teenagers drinking."

In all, the wildfire destroyed 53 homes, 33 outbuildings, one mobile home and 37 vehicles. Another 34 homes and 11 outbuildings were damaged. No one was seriously injured.

Last month, powerful Santa Ana winds fanned brush fires in seven counties that scorched a total of 800 square miles and destroyed 2,196 homes.

On Tuesday, a 19-year-old man, Gorgonio Nava, was ordered to stand trial on a charge of starting a small brush fire in the San Diego County city of Vista during the siege of fires. Nava has pleaded not guilty to committing arson on forest land during a state of emergency.

Malibu was also hit by one of the October fires, losing six homes, two businesses and a church.

Copyright 2007 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.